And there is now data suggesting that bone remodeling is better with these short stems.
What is important to realize is that not all short stems are the same. And that they vary in a variety of ways. For example, the places they contact in the femur. The Trilock is much different as a wedge stem than a circumferentially contacting stem like the ABG-2 or the ARC stem, which is a neck-supported device. This may affect the outcomes.
So, in summary, short stems which engage and fill the proximal metaphysis are reliable and secure well beyond 10 years. What I think we can say, for sure, is these short stems are much easier to remove.
And finally, if you’re doing a direct anterior, it’s a lot easier to use a short stem than it is a standard stem.
Dr. Dorr: So, I guess we ask that question—why should we use it?
So, I designed the first short stem used in the United States. Chit Ranawat and I designed it on a napkin in New Orleans at the Academy in 1981. I put it into four patients and it worked very well for about 18 months.
The failure on these, interestingly enough, was because of the porous coating, which in the early 1980s, was so weak that the implant pulled away from the coating. But the bone did grow in.
A short stem at least proved something.
I still use a current design today, but not in a routine fashion. They’re used most of the time with femurs that are geometrically deformed mostly because of fracture. And I’ve cemented them. And I’ve used them non-cemented. And they all function very well for me. They do function.
I think it’s very clear to understand that these stems function well primarily in type A bone. A recent study out of Korea of 100 patients had 88 that were in type A bone.
The question is “What’s not to like about it?”
There are somethings that are a little bit unique to short stems. You still can get fractures. You can get a calcar fracture if you put it in too big—you can break the medial side off just by the wedge effect. The same wedge effect you get with a blade stem. You can get bone-on-bone impingement. You have to be very, very careful with your biomechanical reconstruction. If you shorten your offset, or you shorten your neck length and you have increased maintenance of the bony neck, you’re going to really increase your risk for bone-on-bone impingement. And you’ll get increased anteversion of the stem.
